It's not exclusively a
"4 stroke" frame. Notice the engine sits snugly in the V saddle. And front wheel distance? That's purely a cosmetic choice in frame style and has no impact or effect on performance.
Perhaps whoever turned you onto the frame was simply doing you the favor of having the ability of putting in a 4-stroke motor vs being stuck with a 2-stoke had you purchased the other frame. If they didn't have that conversation with you, shame on them.
Maybe your longer wheelbase setup doesn't effect performance, maybe it does. I'm not a race bike expert. Though in automobiles, you don't want it. On the cosmetic side, I'm on the fence about the frame, every build I've seen fails to hit my buy button, proportion's are off.
Here's a 2 stoke build on the GT2-A (2-stoke frame)
So, here are the specs for the two different frames. 2-stroke specifc and the 4-stoke/2-stoke frame
SkyHawk Aluminum Bike Frame
GT2-A for 48cc / 66cc
Features:
Built-in 2.4L gas tank
Pedestal front mount allows fitting of all 2 cycle bike engines with either 40 or 50mm front mount stud spacing
26" frame made especially heavy duty for gas engine applications
Available with 135mm rear frame width for either single speed or multi-speed bikes
38mm diameter downtube 70 degrees angle V frame
Material: Aluminum - No gas tank rusting
No other bike frame in the world is especially made for motorization
Seat post angle allows for level carburetor
Big bottom hole for 1 piece pedal crank
Net weight 6.5 lbs; Gross weight 10.50 lbs; Dimension (box) 43.70 in x 6.50 in x 22.24 in
SkyHawk Aluminum Alloy Bike Frame
GT2A-S for 48cc / 66cc 2 Cycle and 4 Cycle
No pedestal mount
Features:
Built-in 2.4L gas tank
Designed for the late style 2-cycle engines with 50mm wide front mount stud spacing, and also accepts 4-cyle engines
26" frame made especially heavy duty for gas engine applications
Available with 135mm rear frame width for either single speed or multi-speed bikes
38mm diameter downtube 70 degrees angle V frame
The GT2S-A frame is made for the new 203 brg engines with the 50mm wide front mount stud spacing for big downtubes. This frame is not to be used with older 2 cycle engines with 40mm wide stud spacing at front mount No other bike frame in the world is especially made for motorization
Seat post angle allows for level carburetor
Big bottom hole for 1 piece pedal crank
Material: Aluminum - No gas tank rusting
Net weight 6.5 lbs; Gross weight 10.50 lbs; Dimension (box) 43.70 in x 6.50 in x 22.24 in
Straight rear drop outs for easy chain tightening.
Cable eyelets for securing all cables.
50mm OD x 43mm ID stem